<!DOCTYPE HTML>
<!--PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">-->
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8">
    <title>JS生成验证码</title>
    <style type="text/css">
        .code {
            background-image: url(code.png);
            font-family: Arial;
            font-style: italic;
            color: Red;
            border: 0;
            padding: 2px 3px;
            letter-spacing: 3px;
            font-weight: bolder;
        }
        .unchanged {
            border: 0;
        }
    </style>
    <script language="javascript" type="text/javascript">
        var code; //在全局 定义验证码
        function createCode() {
            code = "";
            var codeLength = 6;//验证码的长度
            var checkCode = document.getElementById("checkCode");
            var selectChar = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9,'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z');//所有候选组成验证码的字符，当然也可以用中文的

            for (var i = 0; i < codeLength; i++) {
                var charIndex = Math.floor(Math.random() * 36);
                code += selectChar[charIndex];
            }
            //alert(code);
            if (checkCode) {
                checkCode.className = "code";
                checkCode.value = code;
            }
        }

        function validate() {
            var inputCode = document.getElementById("input1").value;
            if (inputCode.length <= 0) {
                alert("请输入验证码！");
            } else if (inputCode != code) {
                alert("验证码输入错误！");
                createCode();//刷新验证码
            } else {
                alert("^-^ OK");
            }
        }
    </script>
</head>
<body onload="createCode()">
<form action="#">
    <input type="text" id="input1" />
    <input type="text" onclick="createCode()" readonly="readonly" id="checkCode" class="unchanged" style="width: 80px" /><br />
    <input id="Button1" onclick="validate();" type="button" value="确定" />
</form>
</body>
</html>